Terms in this set (18)
Definition of Kilocalorie
Definition of nutrient
substance in food for growth, maintenance, repair
My Plate food guide ( Fig 24.1).
FRUITS, GRAINS, VEGETABLES, PROTEIN AND DAIRY
Carbohydrated: uses in the body.
Glucose - fuel used by cells to make ATP
Some cells use fats for energy
Neurons and RBCs ~ entirely on glucose; neurons die quickly without glucose
Excess glucose converted to glycogen or fat and stored
Fructose and galactose converted to glucose by liver before circulation
Fig 24.3: stages involved in processing nutrients.
Stage 1: Digestion in GI tract lumen to absorbable forms. Trasport via blood to tissue cells
Stage 2: Anabolism and catabolism of nutrients to form intermediates within tissue cells
Stage 3: Oxidative breakdown of stage 2 products occurs in mitochondria of tissue cells. CO2 is liberated and H atoms removed are ultimately delivered to molecular oxygen, forming water. Some energy released is used to form ATP
Anabolism and catabolism.
Anabolism - synthesis of large molecules from small ones
Ex. Amino acids proteins
Catabolism - hydrolysis of complex structures to simpler ones
Ex. Proteins amino acids
Chemical reaction of complete glucose oxidation
Complete glucose catabolism requires three pathways
Electron transport chain and oxidative phosphorylation
Function of glycolysis.
Glycolysis, in the cytosol,
breaks down each glucose
molecule into two molecules of
Products of glycolysis only.
Final products of glycolysis
2 pyruvic acid (C3H4O3)
2 NADH + H+ (reduced NAD+)
Net gain of 2 ATP
How many molecules of ATP are synthetized in glycolosis only ?
Where in the cell does glycolysis occur?
Kreb cycle: function, starting molecules, number of ATP molecules formed during Kreb cycle only.
The pyruvic acid then enters
the mitochondrial matrix, where
the Krebs cycle decomposes it to
CO2. During glycolysis and the
Krebs cycle, substrate-level
phosphorylation forms small
amounts of ATP.
Oxidative phosphorylation: Function, very very briefly be able to describe its mechanism (function of thr H+ gradient) .
Directly uses oxygen
NADH + H+ and FADH2 (from glycolysis and Krebs cycle) deliver hydrogen atoms
Hydrogen atoms combined with O2 water
Released energy harnessed ATP by oxidative phosphorylation
Pumped H+ creates electrochemical proton gradient
Created pH gradient; voltage across membrane
H+ attracted to matrix side of membrane by pH gradient and voltage
H+ diffuses back to matrix via ATP synthase electrical current
ATP synthase uses electrical current ATP
When and where does glycogenolysis glycogelysis occur?
Glycogenolysis and gluconeogenesis in the liver
Lipid metabolism: when and where do lipogenesis and lipolysis occur?
Lipogenesis occurs when cellular ATP and glucose levels are high
What are ketone bodies? Examples of ketone bodies
Chemicals that the body makes when there is not enough insulin in the blood and it must break down fat instead of the sugar glucose for energy. The ketone bodies -- acetone, acetoacetate, and beta-hydroxybutyrate -- are toxic acidic chemicals. They build up in the blood and then spill over into the urine. The body can also rid itself of acetone through the lungs. This gives the breath a fruity odor.
Homeostatic imbalance 24.2.
Elevated body temperature depresses hypothalamus
Positive-feedback mechanism (heat stroke) begins at core temperature of 41C increased temperatures
Skin hot and dry; organs damaged
Can be fatal if not corrected
Heat-associated collapse after vigorous exercise
Due to dehydration and low blood pressure
Heat-loss mechanisms still functional
May progress to heat stroke if not cooled and rehydrated promptly
Low body temperature from cold exposure
Vital signs decrease
Shivering stops at core temperature of 30 - 32C
Can progress to coma and death by cardiac arrest at ~ 21C
Inborn errors of metabolism
Cystic fibrosis (see Chapter 22)
Protein metabolism: Fig 24.16.
Proteins deteriorate, so continually broken down and replaced
Amino acids recycled new proteins or different compound
Protein not stored in body
When dietary protein in excess, amino acids
Oxidized for energy
Converted to fat for storage
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